Setting contact coefficients

We have designed our own magnetic gripper for a pick and place application. I was successfully able to import this and visualize the inertias in Gazebo.

But when I visualize the contacts, the vector keeps on moving frantically. Even though the movements of the arm itself is very smooth, when it comes in contact with another object, it starts vibrating. https://youtu.be/eP29QGYoQhY

I dug into PR2 gripper because it behaves very realistically when it is in contact with other objects and tried to implement the contact coefficients